Continuous laser photolysis of samples saturated with carbon monoxide has been used to rapidly prepare concentrated deoxyhemoglobin S samples. Subsequent to deoxygenation, scattering of laser light has been used to monitor the concentration and temperature dependence of the polymerization reaction. Both the concentration dependence of the tenth-time and the time dependence of the process, decrease as the delay time becomes shorter than 100 milliseconds. In addition, in slowly gelling samples, where single domains of polymers are formed in the observed volume (approximately 10 to the minus 9th power cl) there is a marked increase in the scatter of the observed tenth-times. These results have been explained by a mechanism in which gelation is initiated by homogeneous nucleation of polymers in the bulk solution phase, and subsequently, proceeds by heterogeneous nucleation on the surface of existing polymers. A transient spectrometer has been constructed which is capable of measuring absorption spectra of ordinary solutions in a time of 10 nanoseconds. This spectrometer has been used to monitor the transient recombination of carbon monoxide with hemoglobin after photolysis over the time scale from 10 nanoseconds to 10 milliseconds.